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LMR14030-Q1: the charging of bootstrap capacitor

tsuyoshi tokumoto
Expert 2630 points
Part Number: LMR14030-Q1


Hi team,

 Please let me ask you a question about LMR14030-Q1.
 
 I assume the charging of the bootstrap capacitor as follows.
 
 The bootstrap capacitor is charged by an internal regulator
 through a diode.
 The voltage of the internal regulator which is generated from Vin is approximately 5V.
 
 Is my thinking correct?

Best regards.
Tsuyoshi Tokumoto

  • 0
    TI__Expert 5745 points
    Hi
    I don't see any describe about the output voltage of the internal voltage. But the bootstrap is used to turn on the high-side FET, and the FET will be turn off below 3.2V, so the internal regulator is above 3.2V at least. Besides, for the bootstrap cap selection, the cap must be a high-quality ceramic type with the rated 16V or higher, so maybe the voltage will above 5V. In normal, the voltage is 8V when the input bigger than 8V, when the input below 8V, the internal regulator will be linear with input voltage. But I'm not sure about the detail information of the internal regulator in this IC.
    Thank you!
  • 0
    TI__Intellectual 2790 points
    Hi, the regulator is fulfilled by a 5~6V zenner diode tied up to Vin.
  • 0 in reply to Luke Pan
    Expert 2630 points

    Luke-san,

      Thank you very much for your prompt reply.

      I understand that.

    Best regards.

    Tsuyoshi Tokumoto